System and method for automatically mounting a pellicle assembly on a photomask

Abstract

A system and method for automatically mounting a pellicle assembly on a photomask are disclosed. The method includes loading a photomask into a mounting apparatus and loading a pellicle assembly into a back plate of the mounting apparatus opposite the photomask. The back plate includes at least one load cell that measures a force applied by the mounting apparatus to the photomask and the pellicle assembly. The measured force associated with the at least one load cell is received and the pellicle assembly is mounted on the photomask to create a photomask assembly if the measured force is greater than or approximately equal to a minimum force.

Description

RELATED APPLICATION[0001]This application is a Continuation of International Patent Application No. US / 04 / 032890 filed Oct. 5, 2004, which designates the United States and claims the benefit of U.S. Provisional Patent Application Ser. No. 60 / 509,087 entitled “SYSTEM AND METHOD FOR AUTOMATICALLY MOUNTING A PELLICLE ASSEMBLY ON A PHOTOMASK” filed by Ethan M. Frye et al. on Oct. 6, 2003.TECHNICAL FIELD OF THE INVENTION[0002]The present invention relates in general to photomask manufacturing and, more particularly to a system and method for automatically mounting a pellicle assembly on a photomask.BACKGROUND OF THE INVENTION[0003]As semiconductor device manufacturers continue to produce smaller devices, the requirements for photomasks used in the fabrication of these devices continue to tighten. Photomasks, also known as reticles or masks, typically consist of substrates that have an absorber layer formed on the substrate. The absorber layer includes a pattern representing a circuit ima...

AI Technical Summary

Benefits of technology

[0012]Important technical advantages of certain embodiments of the present invention include a pellicle mounting technique that reduces or eliminates adhesion errors during a mounting process. During the mounting process, load cells located in a back plate of a mounting apparatus measure the force being applied to a photomask and a pellicle assembly by the mounting apparatus. If the applied force is greater than a minimum force, the load cells communicate electrical signals to a controller associated with the mounting apparatus. If the controller receives the electrical signals, the mounting process is completed and a conforming photomask assembly is generated. If the controller does not receive the electrical signals, the controller determines that a non-conforming photomask assembly has been formed and the controller prevents the non-conforming product from being removed by an operator of the mounting apparatus.

[0013]Another important technical advantage of certain embodiments of the present invention includes a pellicle mounting technique that provides the ability to accurately monitor and control the force distribution across a photomask and pellicle assembly in a mounting apparatus. The mounting apparatus includes a back plate containing multiple load cells. The load cells measure a force applied by the mounting apparatus at various locations on the pellicle assembly. By providing measurements from different locations, multiple values may be obtained for the total area of the pellicle assembly. The load cells, therefore, may determine if the force distribution across the pellicle assembly is even and may detect failures that cause poor adhesion of the pellicle assembly to the photomask.

Problems solved by technology

As feature sizes of semiconductor devices decrease, the corresponding circuit images on the photomask also become smaller and more complex.

Due to the opaque nature of the absorber layer, inspecting and controlling the adhesion of the pellicle to the photomask is a difficult task.

However, excursions from the normal protocol may not be detected, which can lead to contamination under the pellicle, damage to the membrane, or even damage to the photomask itself.

Current industry standard pellicle application tools do not allow the measurement of the force distribution, making controlling, or even understanding the effect of, this force an impossibility.

However, this regulation is well below the capability needed to accurately monitor and control the force distribution required in the current and future photomask industry.

This arrangement may result in a radial and uneven distribution of the applied force from top to bottom of the pellicle / photomask assembly.

Small variations in setup, fixturing, or milling of the pellicle mounting tool can amplify this uneven distribution, which may cause poor adhesion of the pellicle to the photomask.

In current industry standard equipment, this failure cannot be detected without thorough manual inspection or comprehensive mechanical testing of the pellicle frame and adhesive.

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